By John Snell| January 11, 2016 at 2:41 AM CST - Updated July 2 at 9:15 AM

ST. CHARLES PARISH, LA (WVUE) - From above, you could see the hundreds of people who clambered onto the levee in chilly morning temperatures to watch the Corps of Engineers operate the giant safety valve at the Bonnet Carre Spillway, upriver from New Orleans.

A good bit of water already pushed through the gaps in the spillway needles. Even before the first bay opened.

The Corps unleashed just 20 bays today, a few closest to the Norco office. The others more than half way across the one and a half miles of gates.

Within a few hours, 20,000 cubic feet per second of river water was gushing through the spillway, enough water to fill an Olympic-sized swimming pool in under five seconds.

The floodway stretches six miles from the river to the lake and was completely inundated with water today, turning that mostly dry area into an instant wetland.

In several spots, the first of the river water made it to the lake, cutting new channels through the sand and marsh, or taking the easy route through a canal and instantly inundating a boat dock off Airline Highway.

Within a few weeks, the river water will completely replace the brackish lake water.

Farther upriver, the Corps says it will be at least Thursday if the decision is made to open the Morganza Spillway.

That decision will be based on whether the river meets two benchmarks, the overall flow of the water and how close it comes to flood stage at the Morganza.

For the moment, downstream, the Bonnet Carre takes just enough of the Mississippi, to avoid disaster.